Troubles triggering analog drum machine with arduino and 4066 IC

Other Hardware General Electronics
1

Hello Arduino people!

I'm working on a project where i'm making a sequencer for an old analog drum machine. I got this cute little box called the Yamaha MR10. It's full analog, doesn't sound nearly as good as all the TR machines, but it fun, cheap, and the bass drum is quite good.

Anyway, It only has pre-programmed rhythms, so you can only play cheesy songs.
But! it does have a few pads on the front to trigger some of the samples.
And, looking at the schematic, it shouldn't be too hard to add extra triggers and add some pots for sound control.

I got quite far at building a sequencer (only started using arduino's and programming them really about a week ago) but i'm having some trouble with the triggering.

The way I've got it set up now, is that a pin of the arduino goes hi for about 18ms (i think that's the standard trigger time, doesn't really matter if I change it) and it closes a gate on a 4066 IC

It does work, since the pads are basically on/off buttons themselves, but i do get some distortion.

I notice the sound triggers softer if played with the 4066 IC, and I think (not an expert) it's because the 4066 grounds the outputs when the trigger closes. I notice that the moment I connect the leads to the 4066, the sound triggers once, and after that, it plays softer.

It could also be because the MR10 works on -9 volts..
there's a big schematic here

If I extend the pads with normal push buttons, I get the normal sound..

So basically, what i was wondering, is there another way to trigger the envelopes of this drum machine? or a way to create my own -9v trigger pulses?

Thanks for reading :slight_smile:

2

here's a small W.I.P. video of the build :slight_smile: running a programmed rhythm.
It has a Nokia 5110 LCD as the sequencer screen, and the top 16 buttons of a commodore keyboard as the 16 step program buttons
(and a 4x4 keypad of an old phone as the inst, select and menu options :slight_smile: )

3

If I extend the pads with normal push buttons, I get the normal sound..

Use relays in place of normal push buttons.
Little telecon relays can be driven from Arduino pins directly, here's 15 of them controlled by Atmega1284P for example (5V coil with high resistance)

843×562 151 KB

Example:

4

Ah, that sounds interesting!
I thought relays where only for higher voltage applications.. 230V etc..
Is there any time delay with using relays? Since timing is quite crucial using it in a midi sequencer and all :slight_smile:

will they handle the -9 volt with little resistance?

5

The contacts can handle -9V no problem.
Spec for that relay is on & off in 3mS.
I know at 5mS you can start hearing audio delay as an echo, I think for drums will be just fine.

6

Cool, thanks for the tip. I'll try it out :slight_smile:

7

Aw, that's cheating! Relays? :wink: Build proper level shifters with a couple transistors.

On a phone right now, but when I next get on a computer, I'll try to remember to work up a schematic.

Those pads aren't velocity sensitive are they? (Regarding the comment about quieter sound..)

8

Some call it cheating, some call it less work :slight_smile:

But hey, I'm open to ideas.
The pads are not anything sensitive :stuck_out_tongue: It's just a cheap analog drum computer from 1980's with clicky buttons...